Whooping cough vaccine may still allow some level of infection

Animal tests show pertussis shots stave off symptoms but allow spread of bacteria

The standard U.S. vaccine for whooping cough prevents serious disease in recipients but might allow them to harbor and spread the microbe. A study suggests that recent U.S. outbreaks of whooping cough could have arisen in part from the use of an underachieving vaccine.

Researchers vaccinated infant baboons with the standard three shots against Bordetella pertussis, which causes whooping cough. Other baboons got an older pertussis vaccine that was set aside in the 1990s due to suspected side effects. A third group wasn’t vaccinated. Scientists then exposed the baboons to live pertussis bacteria at age 7 months.

While the unvaccinated baboons got sick, both groups of vaccinated animals had no severe symptoms. But nasal swabs of the animals revealed that baboons given the standard shots still carried the pertussis microbes; subsequent tests showed they could transmit them to unvaccinated baboons. Animals getting the older vaccine cleared the bacteria, researchers at the U.S. Food and Drug Administration in Bethesda, Md., report November 25 in the Proceedings of the National Academy of Sciences.

Citations

J. Wafgel, L.I. Zimmerman and T.J. Merkel. Acellular pertussis vaccines protect against disease but fail to prevent infection and transmission in a nonhuman primate model. Proceedings of the National Academy of Sciences. Published online November 25, 2013. doi: 10.1073/pnas.1314688110.